title: Crossover from weak to strong coupling superconductivity in multi-band systems.
abstract: The study of superconductivity in correlated systems is an exciting area of condensed matter physics. In this paper we consider superconducting ground states in systems described by two-band models with different effective masses. These two bands are coupled through an effective hybridization that can be directly tuned by pressure. We consider the cases of s-wave superconductivity associated with the electrons in a narrow band and also with inter-band pairing. To study the system in the strong coupling regime we introduce the s-wave scattering length a(s), and obtain the superconducting order parameters and the chemical potential as functions of the interaction strength 1/k(F)a(s) along the BCS-BEC crossover at T = 0. Finally, we discuss the phase diagram of this model as a function of external pressure and how our results can be applied for two-band systems as Fe pnictides or heavy fermions. The main result of this study is the occurrence of a superconducting quantum critical point (SQCP) in this two-band model.
authors.affiliation: Instituto de Física, Universidade Federal Fluminense, Campus da Praia Vermelha, Niterói, RJ, 24.210-340, Brazil.
authors.forename: Francisco
authors.initials: F
authors.lastname: Dinóla Neto
authors.forename: Mucio A
authors.initials: MA
authors.lastname: Continentino
authors.forename: Claudine
authors.initials: C
authors.lastname: Lacroix
mesh_terms: D004553:Electric Conductivity; D004583:Electrons; D015233:Models, Statistical; D008962:Models, Theoretical